With many medical instruments, it is desirable for a doctor to be able to bend a portion of the instrument, such as the tip, to suit the anatomy of the patient being treated. The instrument may be bent a number of times during a single procedure to adjust the instrument, and/or the instrument may be bent upon completion of a procedure back to its initial shape for reuse, the subsequent procedure typically requiring further bending. When made from conventional metals, such instruments generally work harden when the same general area is subjected to repeated bending. Progressively, elongation may be reduced, and the force required to bend the instrument may be increased. In addition, the work hardening may make it difficult to return the instrument to its original shape, and sometimes after repeated bending, the instrument will fatigue and fail. In metals frequently used for medical devices, such as stainless steel and aluminum, such failure may occur in only a few cycles of severe bending, resulting in devices having limited reusability. This failure occurs because the stress-strain curve for such metals in the plastic range has a positive slope.
Accordingly, there is a need for medical instruments having improved fatigue life and which may be bent for use, or during use, and returned easily to their original shape, thereby providing bendable instruments that may be more effectively reused.